Stud welding is a general term for joining a metal stud to a workpiece such as a metal plate. A particularly useful stud welding technique is stud arc welding which involves the joining of the base or end of a stud to the workpiece by heating them with an arc drawn between the two components. After proper heating of the two components they are brought together under pressure, such as by use of a stud welding gun, with melting of a portion of the stud and the other component or base metal. The most common stud materials that are welded with the arc weld process are low carbon steel, stainless steel, and aluminum. Generally, in such welding, the stainless steel melt of the stud is diluted from a carbon steel or low alloy steel melt in the weld in an amount of about 20 to 50 percent by weight.
Although stainless steel studs, typically 304 stainless steel, are routinely welded to carbon steel or low alloy steel plate, the problem always exists of the lack of ductility of the weld. Because of the lack of ductility, some normal tests are not met, such as the normal ASME Section IX QW 192.1, 15.degree. bend and re-straighten test of the Boiler and Pressure code. The AWS D1.1 bend test requirement of 7.6.5 is considerably more severe than the ASME requirement so this also cannot be achieved by routine welding of stainless steel studs to carbon steel base plate.
It is an object of the present invention to provide a method for stud welding stainless steel studs to a carbon steel or low alloy steel component in a manner that produces a ductile weld metal.